I do not use GSX. But the starting point of these problems is similar to yours. After trying many advices I found on websites (all were useless to solve the abnormalties) I am at the moment waiting for SU10 which is announced to next week. Sometimes those problems disappear when the SIM is renewed.
And I am facing purple textures on some airports on partail areas of aprons or taxiways, But not in any case. Sometimes it is not possible to start the SIM (after choosing a flight from the globe), especially in case of handcrafted airports. After flying from a not handcrafted airport to a not handcrafted or add-on-airport, it is not possible to switch of the SIM by pressing the “Quit to desktop”-button.